Fendt 8.3.17 – Rear EPC (Electronic Power Control) control module (A005 or A014): Supply voltage (Battery Voltage / Ub 30) is greater than 18 Volts

The system has detected that the supply voltage (Battery Voltage / Ub 30) is greater than 18 Volts. Control is terminated and locked to prevent electrical damage to the module and solenoids.

• 411 Vario COM III
• 412 Vario COM III
• 413 Vario COM III
• 414 Vario COM III
• 415 Vario COM III
• 712 Vario COM III
• 714 Vario COM III
• 716 Vario COM III
• 718 Vario COM III
• 818 Vario COM III
• 820 Vario COM III
• Farmer 400 Vario series
• Favorit 700 Vario series
• Favorit 900 Vario series (916, 920, 924, 926, 930)
• COM III Vario Series (300, 400, 700, 800, and 900 Vario models)

1. 1

   Verify battery voltage at the terminals while the tractor is running; readings climbing above 15V–18V indicate an alternator voltage regulator failure (overcharging cause)

2. 2

   Check if the tractor was recently jump-started using a 24V system, which would immediately trigger this overvoltage code

3. 3

   If battery voltage tests normal (12.6V resting, ~14.2V running), disconnect the harness at the Rear EPC control module (A014) and probe the constant power supply pin (Ub 30) to check for a severe harness short

4. 4

   If physical voltage at the module pin is normal (12V-14V) but the ECU still reports >18V, verify if the internal voltage sensing circuit of the EPC module has failed (module failure cause)

1. 1

   Address the Overcharge

   If the alternator is outputting >18V, immediately shut down the tractor to prevent frying other ECUs.

2. 2

   Replace the Voltage Regulator / Alternator

   Disconnect the battery negative terminal. Remove the serpentine belt, disconnect the electrical connections to the alternator, and unbolt the unit. Install a new alternator or replace the voltage regulator pack on the rear of the existing alternator.

3. 3

   Inspect for Collateral Damage

   Check all fuses on the A013 printed circuit board (specifically F040, F041) and test other tractor functions.

4. 4

   Clear Codes

   Reconnect the battery, start the tractor, and verify the charging voltage is now stable at ~14.2V. Use the tractor's multi-display terminal or the FENDIAS diagnostic tool to clear the 8.3.17 fault code and unlock the rear power lift controls.